(Corrects story throughout to clarify that police, not immigration officials, were involved)

By Kieran Guilbert

LONDON, Feb 26 (Thomson Reuters Foundation) - Foreign domestic workers in Britain who have been exploited or enslaved could be deterred from seeking help after law enforcement visited a support group demanding the whereabouts of one of their members, the head of the charity said on Tuesday.

The unprecedented appearance of law enforcement at an event in London on Sunday may hinder efforts by The Voice of Domestic Workers (VODW) to support abused workers, many of whom are undocumented and living under the radar, said Marissa Begonia.

Begonia said she had thought the officers were immigration officials but a spokesman for London's Metropolitan Police said police officers visited the event at a church hall to follow up on an allegation of assault said to have taken place in January.

"The suspect was not found. Nobody was arrested," he said.

Almost 20,000 visas were granted to overseas domestic workers in 2017 - up from 15,000 in 2014 - and many complain that their employers lock them up, abuse them and withhold pay due to a system that activists say leaves maids powerless.

But foreign maids in Britain - who come mainly from the Philippines, India and Indonesia - often choose to endure abuse, rather than flee and lose a visa, paycheck and place to live.

"It's difficult to convince women (domestic workers) to come forward and get help," Begonia told the Thomson Reuters Foundation before it came to light that police, not immigration officials, were involved in the visit to the event on Sunday.

Begonia said the visitors asked after one of her members and to see a list of attendees at the event. She refused to comply. The police did not comment on the details of the visit.

Prime Minister Theresa May championed the country's landmark 2015 anti-slavery law while interior minister but also declared a "hostile environment" for illegal immigrants, imposing tough new requirements in 2012 for people to prove their legal status.

Britain in 2012 introduced tied visas for domestic workers - removing their right to change employer, bring family members with them or stay longer than half a year.

The government made reforms in 2016, allowing domestic workers to change employers within six months of arrival, pledging to better inform workers of their rights, and granting visas of up to two years for those found to be enslaved

Yet anti-trafficking activists say very few workers are aware of their new rights, that six months is too short to move jobs, and much of the abuse they suffer - from starvation to rape - is not considered modern slavery to the government.

Britain in 2016 announced voluntary information sessions to educate domestic workers and employers, yet there has been no update on when or how they will be implemented, said Kate Roberts, head of office at the Human Trafficking Foundation.

Britain announced in July it would review its 2015 law amid criticism that it is not being used fully to jail traffickers, drive big businesses to stop forced labour, or support victims.

About 7,000 suspected victims of slavery were uncovered in Britain last year, up a third on 2017, according to data that activists said this month raised concerns about the government's ability to support a growing number of survivors.

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